Nrf24L01 2.4 GHz Transceiver

As the nRF24L01 only has a single bit for indicating RF-reception and the
output was desired to be readable on a simple terminal device, a few tricks
were necessary to create a decent display of the 2.4 GHz band. However, even
the shifting of the carrier of a WLAN spot can clearly be seen in the waterfall
display.

As common FR24L01 libraries do not interface well with SPI-lib of the current
Arduino IDE (22), The necessary interface was written from scratch. Some timing is
pushing the limit of the device(s), as we wanted to scan as fast as possible, but
they are working reliably with my setup.

Basically, the setup is very simple. The nRF24L01p is a SPI-device, and you
have to run cables from the Arduino-specific pins to the nRF24L01p-breakout
board. Specifically, the connections are: